The present invention relates to an arrangement for enhancing the cooling capacity of portable personal computers. More particularly, the invention is directed to the aspect of enhancing the power dissipation of portable personal computers (PCS) by transferring heat through a flexible heat pipe which is arranged in operative relationship with a novel hinge structure incorporating link elements pivotably interconnecting a display panel with a bottom keyboard housing so as to impart minimal bending stresses to the flexible heat pipe, and which facilitates transferring the heat into an area at the rear of the display panel.
The capacity and performance of portable personal computers, such as laptop computers, notebook computers or the like, has recently been enhanced to such an extent that; for example, since the beginning of 1996, the thermal dissipation requirements of portable personal computers (PCS) have increased from about 10 watts to 20 watts and even higher values. This increase in the thermal dissipation requirements is a result of ever increasing CPU performance and additional functionality; such as DVD, modem, audio and the like, which are provided by future PCS. As eludicated in an article by Albert Yu, "The Future of Microprocessors", IEEE Micro, December 1996, pages 46 through 53, the trend of increasing power dissipation in the form of heat for portable personal computers will continue in the foreseeable future. Accordingly, at the widely employed A4 form factor for a portable personal computer; for instance, the cooling limit for a portable PC without a cooling fan is currently approximately 15 to 20 watts. Thus, providing a greater cooling capacity than the current limits in order to meet the anticipated thermal dissipation requirements of future portable personal computers, represents not only a potential competitive advantage in industry, but also provides a significant product differentiation from currently available and commercially sold portable personal computers.
In order to meet the requirements for enhancing the cooling capacities of portable personal computers, pursuant to the invention, a personal computer, especially such as a laptop computer having an openable display panel and a keyboard articulated to the bottom thereof, incorporates a flexible heat pipe for transferring heat in an operative relationship with the hinge mechanism of the display panel which connects the latter to the bottom housing such that only minimal bending stresses are encountered by the heat pipe and which essentially transfers the heat into an area towards the rear of the display. At that location, the availability of an increased surface area and the presence therein of relatively few electronics facilitates an increased degree of heat dissipation into the ambient air or surroundings.
An extremely valuable area for dissipating heat on a laptop computer is the back of the display. This area is normally not used effectively because very few heat generating components are located in this area. Furthermore, it is difficult to transfer more heat to this area from the lower portion or bottom housing of the laptop computer because the means to implement this has to pass through a hinge forming the interconnection between the lower portion of the laptop computer and the display panel. Additionally, it is difficult to locate heat generating components, such as the CPU, in this area because the large number of signal wires which must pass through the hinge in order to communicate with the other components located in the lower portion of the laptop computer.
A well known device for conducting heat efficiently is a heat pipe. The heat pipe normally consists of a length of tubing, usually comprising copper, which is hermetically sealed with a fluid contained therein under a critical pressure such that, when one end of the pipe is in contact with a warm body, the heat from the warm body causes the fluid to boil. The normally vaporous fluid travels to the colder end of the tube and condenses thus taking energy therewith to the other end of the tube. Transfer rates of greater than 100 times that of conducting through copper can be achieved in this manner. Moreover, the length of the tube has little impact on the transfer rate of the heat pipe.